If you're not already using emacs I don't know if the learning curve is worth it just for org mode. But as an example of what it can do (with a little customiz

If you're not already using emacs I don't know if the learning curve is worth it just for org mode. But as an example of what it can do (with a little customization), I use org mode for writing fiction. I give each scene a header kind of like a film script slug line. They automatically become foldable, so I can collapse them and just read the headers as an outline. Scenes can be rearranged at will. I can also work backwards from the headers, starting with an outline then filling in the scenes. I can also throw in todo list items wherever I want, on their own or interspersed with the text as reminders for things I want to go back to and edit. Then I have the exporter strips out all the org mode formatting, headers, etc and spit out the text in double spaced manuscript format. It's the best writing tool I've ever used, with the possible exception of Scrivener.